Regarding your first question, is it offensive to think of Krishna's Pastimes while chanting, I think you should know that it is not offensive, but rather it is required. One must try for the point when he simply hears Krishna and immediately all of Krishna, His Pastimes, His Form, His Quality, are in his thoughts. So to always be immersed in thoughts of Krishna this is our process. When we are full in Krishna then where there can be any chance for maya in us? So this is our duty to remember Krishna's Pastimes.
Letter to Sivananda, 4 December, 1968